The objectives of the project remain to study the uniqueness of cartilage, a tissue resistant to both capillary and tumor invasion. We have isolated from hyaline cartilage an anti-invasion factor (AIF) which contains a low molecular weight cationic protein that acts as a mammalian collagenase inhibitor. Collagenases released by both normal and neoplastic cells can be inhibited by this protein. Isolated tumor cells (human osteosarcoma or metastatic mammary carcinoma cells) and endothelial cells and fibroblasts as controls will be studied in culture for their responsiveness to AIF. The proposed research intends to identify the biologically active component of AIF.